Experimental investigation of surface flow pattern on truncated cones in Mach 5 flow: influence of truncation ratio

The flow characteristics on a truncated cone with a cylinder were experimentally investigated in a Mach 5 flow with a Reynolds number 3.8 × 105, based on the cylindrical diameter. Two different truncation ratios of 0.5 and 0.7 were used. The incidence angle varied from −12 to 0° with 3° intervals to investigate the influence of the truncation ratio on the surface flow pattern. The measurement techniques: unsteady pressure-sensitive paint (anodized aluminium method), color Schlieren photography, and surface oil flow were used. It was found that the distance of the external shock wave from the conical surface depends on the truncation ratio, and the surface pressure on the conical portion increases when the external shock wave moves closer to the model surface. The “external” shock wave denotes a detached shock wave and the “internal” one is the shock wave formed between the detached bow shock wave and the model surface. In the higher truncation ratio at the higher incidence angle, the internal shock wave induced by the flow separation on the conical surface impinges on the external shock wave, which results in its reflection. This reflection leads to the pressure increase on the model surface. On the other hand, this reflection does not appear in the lower truncation ratio. In spite of the different truncation ratios, the angle of the internal shock wave is identical at the same incidence angle. From the oil flow results, the wall shear stress on the leeward conical surface is lager in the higher truncation ratio model

Flow structure generated by laser-induced blast wave propagation through the boundary layer of a flat plate

Laser energy deposition generates localized flow structures that can be used as flow control devices in high-speed flows. In the present study, the interaction between a laser-induced blast wave and an incoming laminar boundary layer on a flat plate was experimentally investigated at a Mach 5 flow with three different unit Reynolds numbers. A hemispherical laser-induced blast wave (LIBW) is induced by focusing a 532 nm pulsed Nd:YAG laser beam on the surface of the plate. The hemispherical shaped fore wave front of the LIBW is locally transformed to an oblique shape, which results in a laser-induced oblique shock wave (LIOSW). As LIOSW propagates through the laminar boundary layer increases its thickness. With laser energy deposition near the leading edge of the flat plate, the LIOSW interacts and influences the leading edge shock wave (LSW). This interaction could contribute to the modulation of the LSW in scramjet intakes. A weak shock limb generated at the shape transition point of the LIBW or thermal spot due to laser-induced gas breakdown causes the boundary layer perturbation. The geometrical pattern produced due to the interaction between the LIOSW and the disturbed boundary layer remains similar to itself as it grows with time as well as at different local Reynolds numbers, to 2.2 x 105 to 5.7 x 105

Pressure-Sensitive Paint: Effect of Substrate

There are numerous ways in which pressure-sensitive paint can be applied to a surface. The choice of substrate and application method can greatly affect the results obtained. The current study examines the different methods of applying pressure-sensitive paint to a surface. One polymer-based and two porous substrates (anodized aluminum and thin-layer chromatography plates) are investigated and compared for luminescent output, pressure sensitivity, temperature sensitivity and photodegradation. Two luminophores [tris-Bathophenanthroline Ruthenium(II) Perchlorate and Platinum-tetrakis (pentafluorophenyl) Porphyrin] will also be compared in all three of the substrates. The results show the applicability of the different substrates and luminophores to different testing environments

Similarity Analysis: Revealing the Regional Difference in Geomorphic Development in Areas with High and Coarse Sediment Yield of the Loess Plateau in China

The development of loess landforms is controlled by underlying, pre-existing paleotopography. Previous studies have focused on the inheritance of loess landform and the control of underlying paleotopography on modern terrain based on the digital elevation model (DEM), while the similarities and differences between modern terrain and underlying paleotophotography have not been directly spatialized. In this study, areas with high and coarse sediment yield (AHCSY) in the Loess Plateau of China were selected to form the study area, and the DEM of the study area’s underlying paleotophotography was reconstructed using detailed geological maps, loess thickness maps, and underlying paleotopographic information. The hypsometric integral (HI) and spatial similarity analysis methods were used to compare the spatialized difference between underlying and modern terrain of the Loess Plateau from the perspectives of the landform development stage and surface elevation, respectively. The results of the HI method demonstrate that essentially, there are similarities between the geomorphologic development stages of underlying and modern terrain, and only some local differences exist in some special areas. The results regarding the spatialized coefficient of relative difference and the Jensen–Shannon divergence demonstrate that the thicker the loess is, the weaker the similarity is, and vice versa. Meanwhile, according to the present loess landform division, the order of regional similarity from low to high is as follows: loess tableland, broken loess tableland, hilly regions, dunes, and the Yellow River Trunk. The use of the similarity analysis method to analyze similarities between underlying and modern terrain plays an important role in revealing the inheritance of loess landforms

Experimental investigation of surface flow pattern on truncated cones in Mach 5 flow: influence of truncation ratio

The flow characteristics on a truncated cone with a cylinder were experimentally investigated in a Mach 5 flow with a Reynolds number 3.8 × 105, based on the cylindrical diameter. Two different truncation ratios of 0.5 and 0.7 were used. The incidence angle varied from −12 to 0° with 3° intervals to investigate the influence of the truncation ratio on the surface flow pattern. The measurement techniques: unsteady pressure-sensitive paint (anodized aluminium method), color Schlieren photography, and surface oil flow were used. It was found that the distance of the external shock wave from the conical surface depends on the truncation ratio, and the surface pressure on the conical portion increases when the external shock wave moves closer to the model surface. The “external” shock wave denotes a detached shock wave and the “internal” one is the shock wave formed between the detached bow shock wave and the model surface. In the higher truncation ratio at the higher incidence angle, the internal shock wave induced by the flow separation on the conical surface impinges on the external shock wave, which results in its reflection. This reflection leads to the pressure increase on the model surface. On the other hand, this reflection does not appear in the lower truncation ratio. In spite of the different truncation ratios, the angle of the internal shock wave is identical at the same incidence angle. From the oil flow results, the wall shear stress on the leeward conical surface is lager in the higher truncation ratio model

A Multi-Criteria Framework for Identification of Gully Developmental Stages Based on UAV Data—A Case Study in Yuanmou County, Yunnan Province, SW China

Gully erosion is a common form of soil erosion in dry-hot valleys, and it often brings serious land degradation. A multi-criteria method integrating the characteristics of the longitudinal profile (LP), the cross profile (CP) and the knickpoints of gullies was applied to identify the development stage of gullies in Yuanmou County, Yunnan Province, in southwestern China. Firstly, based on the high-resolution data sources produced by an unmanned aerial vehicle (UAV), 50 gullies were selected as the typical ones in Tutujiliangzi and Shadi village. The LPs were extracted, and their morphological indices, information entropy and fitting functions were calculated. The morphological characteristics of the CPs and the presence or absence of knickpoints were recorded. The results show that the period of the gullies in Tutujiliangzi and Shadi is dominated by the deep incision period and the equilibrium adjustment period, which means that most gullies are in the period of the severe erosion stage. Among the gullies, 13 LPs’ morphological index is between 0.636 and 0.933, and the morphology of the LP presents an upward convex shape; the cross profiles are mainly V-shaped and U-shaped. Thirty-two LPs’ morphological index is between 1.005~2.384, which presents a slightly concave shape; the cross profiles are mainly repeated U-shapes. The remaining five LPs have a morphological index of 0.592, 0.462, 1.061, 1.344 and 0.888, respectively; the LPs of upstream and downstream are different. The LPs of the Tutujiliangzi gullies are nearly straight lines and slightly concave, while those of the Shadi village gullies are convex and nearly straight lines. The knickpoints and step-pools in Shadi village are more developed, while the gullies in Tutujiliangzi develop more rapidly. This study shows that in counties with similar conditions, these conditions such as temperature and precipitation, local topographic changes, soil properties and vegetation conditions have obvious effects on the development of gullies

Poor prognosis of nucleophosmin overexpression in solid tumors: a meta-analysis

Abstract Background Nucleophosmin is a non-ribosomal nucleolar phosphoprotein that is found primarily in the nucleolus region of cell nucleus, plays multiple important roles in tumor processes. Accumulated previous studies have reported a potential value of NPM acted as a biomarker for prognosis in various solid tumors, but the results were more inconsistency. We performed this meta-analysis to precisely evaluate the prognostic significance of NPM in solid tumors. Methods Clinical data were collected from a comprehensive literature search in PubMed, Web of Science, Embase, and China National Knowledge Infrastructure databases (up to October, 2017). A total of 11 studied with 997 patients were used to assess the association of NPM expression and patients’ overall survival (OS). The hazard ratio (HR) or odds ratio (OR) with its 95% confidence intervals (CI) were calculated to estimate the effect. Results The pooled results indicated that higher expression of NPM was observably correlated with poor OS in solid tumor (HR = 1.85, 95% CI: 1.44–2.38, P < 0.001). Furthermore, high expression of NPM was associated with some phenotypes of tumor aggressiveness, such as tumor stage (4 studies, III/IV vs. I/II, OR = 5.21, 95% CI: 2.72–9.56, P < 0.001), differentiation grade (poor vs. well/moderate, OR = 1.82, 95% CI: 1.01–3.27, P = 0.046). Conclusion This meta-analysis indicated that NPM may act as a valuable prognosis biomarker and a potential therapeutic target in human solid tumors